Lead oxide mills



Oct. 5, 1965 T. B. STAMP 3,210,164

LEAD OXIDE MILLS Filed Jan. 5, 1965 2 Sheets-Sheet 1 I I l l I I l l l II I l 12 L J 9 8 ::::f? 8 y W 5-:5-1-1-1 F IGJ.

T. B. STAMP LEAD OXIDE MILLS Oct. 5, 1965 2 Sheets-Sheet 2 Filed Jan. 5, 1963 FIG2.

United States Patent LEAD OXIDE MILLS Thomas B. Stamp, Walkden, Manchester, England,

assignor to The Chloride Electrical Storage Company Limited, London, England, a British company Filed Jan. 3, 1963, Ser. No. 249,272 Claims priority, application Great Britain, Jan. 5, 1962, 487/62 6 Claims. (Cl. 23-286) This invention relates to lead oxide mills of the type wherein a perforated rotary drum is charged with pieces of lead to be tumbled in a stream of air for the production of the oxide.

In such mills, the perforated drum is surrounded by an arrangement of screens which rotate therewith, the drum and screen assembly being mounted for rotation in an outer closed stationary casing. The oxide which is formed drops away from the lead charge, through the perforated drum, through the surrounding screen and collects at the bottom of the outer casing from where it is discharged. Hitherto the supply of air necessary for the production of the oxide has been introduced into the closed casing at one or more inlets in the side thereof.

The object of the present invention is to provide a uniformly distributed flow of air up through the casing and the rotary drum, whereby the output of oxide is increased and the quality of the oxide is both improved and made more uniform. A further object is to provide means whereby the flow of air may be measured and controlled as required.

In accordance with the invention a lead oxide mill of the type referred to includes a stationary outer casing and a perforated drum mounted for rotation therein, the said casing being adapted to be connected to a source of air and having means located beneath the drum for distributing the air entering and flowing through the casing over substantially the full length and width of the drum.

Preferably the casing includes an air manifold thereon for connection to the source of air, and the said air distribution means may comprise a plurality of spaced tubes connected to the manifold and extending across the casing beneath the drum, each tube having a plurality of air outlet ports spaced along its length.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIGURE 1 is a side elevation of a mill in accordance with the invention,

FIGURE 2 is an end elevation of the mill shown in FIGURE 1, and

FIGURE 3 is an enlarged cross-section of a cross tube.

The closed outer casing of the lead oxide mill includes a rectangular central section 1, a lower section 2 of inverted conical shape, and an upper section 3 which is of substantially an inclined conical shape. A rotary drum 4 and its surrounding screens are mounted for rotation within the casing about an axis which is level with the top of the central rectangular section 1. The apex of the upper conical section 3 is provided with an air outlet or exhaust 5, and the apex of the lower conical section is provided with a valve controlled outlet 6 for continuously discharging the oxide as it falls from the drum 4.

An air inlet pipe 7 connects to manifolds 8 secured by means of flanges to the end walls of the casing at a level below that of the drum 4 and extending across substantially the full width of the casing wall at right angles to the axis of the drum. A series of spaced cross-tubes 9 extend from the manifolds 8 at right angles thereto, running across the interior of the casing and below the drum 4 along the full length thereof. The inlet pipe 7 connects to the centre of the manifolds 8 which slope upwardly at each side therefrom, whereby the tubes 9 are staggered upwardly from the centre in the two banks, one towards each side of the casing. The banks of tubes 9 thus follow very approximately the curvature of the perforated wall of the drum 4 above, and no one tube 9 is a distance from the periphery of the drum 4 substantially greater than the distance of another tube therefrom.

It will be appreciated that the said tubes lie in the path of the oxide as it falls away from the drum and its surrounding screens. Accordingly, as shown in FIG- URE 3, the tubes are made of triangular shape in crosssection and are mounted apex upwards, the air emerging from them through a plurality of spaced openings or ports 11 provided in their base portions, that is initially downwardly. Thus the said ports will not h come blocked by the falling oxide while in addition the triangular shape of the tubes 9 provides least obstruction to the oxide and does not introduce traps or ledges on which it could collect.

A venturi, orifice plate or other air measuring device (not shown) fitted with flow indicating equipment may be coupled to the hollow shaft 12 on which the rotary drum is mounted, whereby the flow of air through the drum may be measured. The air inlet pipe is fitted with dampers 13 or other flow control devices whereby the air flow to the casing can be regulated as necessary.

The inclination of the upper conical section 3 of the casing is away from the direction of rotation of the drum 4, so that the shape of the upper part of the casing acts as a baffle tending to prevent any lead oxide particles which may become entrained in the air stream from reaching the air exhaust outlet 5.

The arrangement of tubes 9 described above provides a flow of air up through the interior of the casing which is uniformly distributed across substantially the full width and length of the casing and of the drum 4. Furthermore the sloping of the banks of pipes, whereby the distance of each pipe from the adjacent part of the periphery of the drum is very approximately the same for each pipe, ensures that the rate of flow of air when it reaches the perforated drum will be substantially uniform throughout.

This improved distribution of air and its more uniform flow, which in addition can be adjusted and controlled, results in a more uniform and controlled quality of oxide being produced, and also provides an increase in the rate of production. Thus not only is the drum as a whole provided with a better distributed and more uniform supply of air, but in addition, the oxide which is formed and which falls away from the screens surrounding the drum has itself to pass through a flow of air distributed uniformly across the whole casing. The falling oxide which is still hot from the exothermic reaction of oxidation firstly becomes more fully oxidised and then becomes cooled, but in no one region of the casing does this occur to a substantially greater or less extent than anywhere else in the casing.

What I claim is:

1. A lead oxide mill comprising a stationary casing having a lower section of inverted conical shape, an air outlet at the top of the casing, an outlet for lead oxide at the bottom of the lower casing section, a perforated drum rotatably mounted within the casing, an inlet in the drum for introducing lead pieces thereinto for conversion to lead oxide, a manifold system secured to the casing below the drum, but above the lower casing section and extending transversely across the casing, a plurality of transversely spaced tubes connected to the manifold system and extending longitudinally of the casing, the tubes having steeply inclined side walls to avoid lodgement of oxide thereon, air outlet means extending along the length of each tube in the form of a plurality of ports spaced along the underside of the tube, and air delivery means connected to the manifold system for feeding air via the manifold system and tubes over substantially the full length and width of the drum.

2. A lead oxide mill comprising a stationary casing having a lower section of inverted conical shape, an air outlet at the top of the casing, an outlet for lead oxide at the bottom of the lower casing section, a perforated drum rotatably mounted within the casing, an inlet in the drum for introducing lead pieces thereinto for conversion to lead oxide, a manifold system secured to the casing below the drum but above the lower casing section and extending transversely across the casing, a plurality of transversely spaced tubes connected to the manifold system and extending longitudinally of the casing, the cross-sectional shape of the tubes being an isosceles triangle with a base substantially shorter in length than that of the equal sides, air outlet means extending along the length of each tube in the form of a plurality of ports spaced along the underside of the tube, and air delivery means connected to the manifold system for feeding air via the manifold system and tubes over substantially the full length and width of the drum.

3. A lead oxide mill comprising a stationary casing having a lower section of inverted conical shape, an air outlet at the top of the casing, an outlet for lead oxide at the bottom of the lower casing section, a perforated drum rotatably mounted within the casing, an inlet in the drum for introducing lead pieces thereinto for conversion to lead oxide, a manifold system secured to the casing below the drum but above the lower casing section and extending transversely across the casing, a plurality of transversely spaced tubes staggered upwardly from the centre of the casing in two banks, one towards each of two opposite sides of the casing, and connected to the manifold system and extending longitudinally of the casing, the crosssectional shape of the tubes being an isosceles triangle with a base substantially shorter in length than that of the equal sides, air outlet means extending along the length of each tube in the form of a plurality of ports spaced along the underside of the tube, and air delivery means connected to the manifold system for feeding air via the manifold system and tubes over substantially the full length and width of the drum.

4. A lead oxide mill comprising a stationary casing having a lower section of inverted conical shape, an air outlet at the top of the casing, an outlet for lead oxide at the bottom of the lower casing section, a perforated drum rotatably mounted within the casing, an inlet in the drum for introducing lead pieces thereinto for conversion to lead oxide, a manifold system secured to the casing below the drum but above the lower casing section and extending transversely across the casing, a plurality of transversely spaced tubes staggered upwardly from the centre of the casing in two banks, one towards each of two opposite sides of the casing, and connected to the manifold system and extending longitudinally of the casing, the cross-sectional shape of the tubes being an isosceles triangle with a base substantially shorter in length than that of the equal sides, and the manifold system comprisingtwo V-shaped manifolds, one arranged at and communicating with the tubes at one end and the other at the other end of the tubes, air outlet means extending along the length of each tube in the form of a plurality of ports spaced along the underside of t tube, and air delivery means connected to the manifold system for feeding air via the manifold system and tubes over substantially the full length and width of the drum.

5. A lead oxide mill comprising a stationary casing having a lower section of inverted conical shape, an air outlet at the top of the casing, an outlet for lead oxide at the bottom of the lower casing section, a perforated drum rotatably mounted within the casing, an inlet in the drum for introducing lead pieces thereinto for conversion to lead oxide, a manifold system secured to the casing below the drum but above the lower casing section and extending transversely across the casing, a plurality of transversely spaced tubes staggered upwardly from the centre of the casing in two banks, one towards each of two opposite sides of the casing, and connected to the manifold system and extending longitudinally of the casing, the cross-sectional shape of the tubes being an isosceles triangle with a base substantially shorter in length than that of the equal sides, and the manifold system comprising two V-shaped manifolds, one arranged at and communicating with the tubes at one end and the other at the other end of the tubes, air outlet means extending along the length of each tube in the form of a plurality of ports spaced along the underside of the tube, and air delivery means connected to the manifold system for feeding air via the manifold system and tubes over substantially the full length and width of the drum, the air delivery means including a duct connected to the centres of the manifolds, and means within the duct for regulating the air flow to the casing.

6. A lead oxide mill comprising a stationary casing, having a lower section of inverted conical shape, an outlet for lead oxide at the bottom of the lower casing section, a perforated drum rotatably mounted within the casing having a lower section of inverted conical shape, an air outlet at the top of the casing, an outlet for lead oxide at the bottom of the lower casing section, a manifold system secured to the casing below the drum but above the lower casing section and extending transversely across the casing, a plurality of transversely spaced tubes staggered upwardly from the centre of the casing in two banks, one towards each of two opposite sides of the casing, and connected to the manifold system and extending longitudinally of the casing, the cross-sectional shape of the tubes being an isosceles triangle with a base sub stantially shorter in length than that of the equal sides, and the manifold system comprising two V-shaped manifolds, one arranged at and communicating with the tubes at one end and the other at the other end of the tubes, air outlet means extending along the length of each tube in the form of a plurality of ports spaced along the underside of the tube, air delivery means connected to the manifold system for feeding air via the manifold system and tubes over substantially the full length and width of the drum, the air delivery means including a duct connected to the centres of the manifolds, and means within the duct for regulating the air flow to the casing, and an air outlet at the upper part of the casing and inclined away from the direction of rotation of the drum so that the casing acts as a bathe tending to prevent lead oxide entrained in the air stream from reaching the air outlet.

References Cited by the Examiner UNITED STATES PATENTS 1,910,280 5/33 Chamberlain 23l46 MORRIS O. WOLK, Primary Examiner.

JAMES H. TAYMAN, 111., Examiner. 

1. A LEAD OXIDE MILL COMPRISING A STATIONARY CASING HAVING A LOWER SECTION OF INVERTED CONICAL SHAPE, AN AIR OUTLET AT THE TOP OF THE CASING, AN OUTLET FOR LEAD OXIDE AT THE BOTTOM OF THE LOWER CASING SECTION, A PERFORATED DRUM ROTATABLY MOUNTED WITHIN THE CASING, AN INLET IN THE DRUM FOR INTRODUCING LEAD PIECES THEREINTO FOR CONVERSION TO LEAD OXIDE, A MANIFOLD SYSTEM SECURED TO THE CASING BELOW THE DRUM, BUT ABOVE THE LOWER CASING SECTION AND EXTENDING TRANSVERSELY ACROSS THE CASING, A PLURALITY OF TRANSVERSELY SPACED TUBES CONNECTED TO THE MANIFOLD SYSTEM AND EXTENDING LONGITUDINALLY OF THE CASING, THE TUBES HAVING STEEPLY INCLINED SIDE WALLS TO AVOID LODGEMENT OF OXIDE THEREON, AIR OUTLET MEANS EXTENDING ALONG THE LENGTH OF EACH TUBE IN THE FORM OF A PLURALITY OF PORTS SPACED ALONG THE UNDERSIDE OF THE TUBE, AND AIR DELIVERY MEANS CONNECTED TO THE MANIFOLD SYSTEM FOR FEEDING AIR VIA THE MANIFOLD SYSTEM AND TUBES OVER SUBSTANTIALLY THE FULL LENGTH AND WIDTH OF THE DRUM. 